Characterization of the Cell Surface and Cell Wall Chemistry of Drinking Water Bacteria by Combining XPS, FTIR Spectroscopy, Modeling, and Potentiometric Titrations

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• 作者：Jesú ; s J. Ojeda ; Marí ; a E. Romero-Gonz&aacute ; lez ; Robert T. Bachmann ; Robert G. J. Edyvean ; Steven A. Banwart
• 刊名：Langmuir
• 出版年：2008
• 出版时间：April 15, 2008
• 年：2008
• 卷：24
• 期：8
• 页码：4032 - 4040
• 全文大小：232K
• 年卷期：v.24,no.8(April 15, 2008)
• ISSN：1520-5827

文摘

Aquabacterium commune, a predominant member of European drinking water biofilms, was chosen as a modelbacterium to study the role of functional groups on the cell surface that control the changes in the chemical cell surfaceproperties in aqueous electrolyte solutions at different pH values. Cell surface properties of A. commune were examinedby potentiometric titrations, modeling, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR)spectroscopy. By combining FTIR data at different pH values and potentiometric titration data with thermodynamicmodel optimization, the presence, concentration, and changes of organic functional groups on the cell surface (e.g.,carboxyl, phosphoryl, and amine groups) were inferred. The pH of zero proton charge, pH_zpc = 3.7, found fromtitrations of A. commune at different electrolyte concentrations and resulting from equilibrium speciation calculationssuggests that the net surface charge is negative at drinking water pH in the absence of other charge determining ions.In situ FTIR was used to describe and monitor chemical interactions between bacteria and liquid solutions at differentpH in real time. XPS analysis was performed to quantify the elemental surface composition, to assess the local chemicalenvironment of carbon and oxygen at the cell wall, and to calculate the overall concentrations of polysaccharides,peptides, and hydrocarbon compounds of the cell surface. Thermodynamic parameters for proton adsorption arecompared with parameters for other gram-negative bacteria. This work shows how the combination of potentiometrictitrations, modeling, XPS, and FTIR spectroscopy allows a more comprehensive characterization of bacterial cellsurfaces and cell wall reactivity as the initial step to understand the fundamental mechanisms involved in bacterialadhesion to solid surfaces and transport in aqueous systems.